SELECTIVE SORPTION OF FERRIC ION ONTO CROSS-LINKED POLY(VINYL BENZALDOXIME)

A crosslinked sorbent containing approximately 35 mol% vinyl benzaldoxime repeat units has been prepared by carrying out the Sommelet reaction on chloromethylated polystyrene of 350-1200 mum bead size followed by reaction of the resulting aldehyde with hydroxylamine. The sorbent exhibits strong binding and a high degree of preference (> 95%) for Fe(III), in low concentrations in aqueous media, in the presence of up to 10-fold molar excess of other metals, such as Cu(II), Fe(II), Ni(II), Co(II), Mn(II) and Zn(II). The sorption preference for Fe(III), however, decreases at higher mole ratios. Thus, with 100-fold molar excess of Mn(II), Ni(II), Co(II), Zn(II) and Cu(II) in binary mixtures, the Fe(III) sorption drops to 80, 70, 65, 60 and 30%, respectively, of its single sorption. The sorbed Fe(III) is readily stripped by both 1 N HCl and 1 N H2SO4. The rate of sorption of Fe(III) from a very dilute solution in a high stirred system is in agreement with chemical-reaction control in the initial stages, while at higher conversions mixed control mechanisms involving both chemical and diffusional resistances appear likely.